What we want to do is to fill out the whole second row with the correct colours.
In the picture below, I want to put the bottom blue in the middle column onto the left middle row. The reason for this is because the other edge of that bottom blue is red so if I put it on the left edge, it will fit with the blue on one side and red on the other. This may not make sense yet, but take a look at the pictures below.
This to This
To do this make the blue side facing you and use this algorithm:
Lets say you want to move the bottom piece to the right side. For example I want the green in the picture below to move to the the right side and fill in with the red. I would use this algorithm.
This to This
Once you have completed all of the second/middle row and make it all the correct colour, you can move onto the third step.
